Winchester NATO-Spec Navy Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot consistency. All primers are consistently and rigorously examined for regularity and sensitivity at temperatures and conditions much over and above the number winchester 41 primers of regular usage. Winchester guarantees very carefully-controlled weights of primer mixtures, consistency in measurement and excellent, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.